Valve operating cam device for internal combustion engine

ABSTRACT

Three cam lobes formed integrally with a rotary camshaft are employed for operating the valves of a three-valve internal combustion piston engine. The center cam is made larger than one of the other cams in every radial direction to facilitate grinding of the external cam surfaces.

United States Patent Ohsaki et al.

VALVE OPERATING CAM DEVICE FOR INTERNAL COMBUSTION ENGINE Inventors: Kiyoshi Ohsaki, Toda; Morio Takahashi, Toyohashi. both of Japan Assignee: Honda Giken Kogyo Kabushiki Kaisha, Tokyo, Japan Filed: July 16, 1974 Appl. No.: 488,917

Foreign Application Priority Data July 31, 1973 Japan 48-89872 US. Cl. 123/90.6; 74/567; l23/90.17 Int. Cl. F011 l/04 Field of Search 123/906, 90.17; 74/567 May 13, 1975 [56] References Cited UNITED STATES PATENTS 1,185.516 5/1916 MacViear 123/901) 2,209,496 7/1940 Watson 123/9116 3 045 657 7/1962 Sampietro 123/901: 3,139,870 7/1964 Sampietro 123/901;

Primary E.\'aminerManuel A. Antonakas Assistant Examiner-Daniel .1. O'Connor Attorney, Agent, or Firm-Lyon & Lyon [57] ABSTRACT Three cam lobes formed integrally with a rotary camshaft are employed for operating the valves of a threevalve internal combustion piston engine. The center cam is made larger than one of the other cams in every radial direction to facilitate grinding of the external cam surfaces.

2 Claims, 3 Drawing Figures PATENTEI] HAY I 3l975 1 VALVE OPERATING CAM DEVICE FOR INTERNAL COMBUSTION ENGINE Three-valve internal combustion engines have an intake and exhaust valve for each of the main combustion chambers, and are provided with an intake valve for each of the auxiliary combustion chambers. The valves are operated by means of a rotary camshaft having a separate cam lobe for operating each of said three valves. The middle cam lobe is relatively narrow because it is used to operate the auxiliary intake valve which is much smaller than the other valves and requires smaller operating forces. In conventional construction, the three cam lobes are grouped together on the rotary camshaft, and the center cam lobe between the other two lobes is narrower in axial width and smaller in radial dimensions. Accordingly, a thin grinding wheel must be employed for grinding the outer surface of the central cam lobe in order to reach in between the two outside cam lobes which have greater radial dimensions. The narrow grinding wheel is subject to undesirable breaking or chipping.

ln accordance with this invention the radial dimensions of the central cam lobe are made larger than one of the outside cams in every angular position of the shaft. In this way, relatively wide grinding wheels may be employed for grinding the individual surfaces of all three cam lobes.

In the drawings:

FIG. 1 is a side elevation showing a preferred form of this invention.

FlG. 2 is a sectional elevation.

FIG. 3 is a side elevation showing a conventional camshaft construction.

Referring to the drawings, the outer cam lobes 2 and 3 are mounted on each side of the central cam lobe 4. All of these cam lobes are integrally formed on the rotary camshaft 1. In accordance with this invention, the radial dimensions of the middle cam lobe 4 are larger at every angular position of the shaft than the corresponding radial dimensions of the adjacent cam lobe 2. Thus, as shown in FIG. 2, the silhouette of the cam lobe 4 is larger than that of the cam lobe 2.

In the conventional arrangement shown in FIG. 3, the outer cam lobes 6 and 7 each have greater radial dimensions than the middle cam lobe 8. Accordingly, a narrow grinding wheel 9 is required to grind the surface of the middle cam lobe 8 in order that it may reach in between the grinding wheels 10 and 11 and cam lobes 6 and 7 to grind the outer surface of the middle lobe 8. Such a narrow grinding wheel 9 is subject to undesirable chipping and breaking.

When the middle cam lobe 4 is larger than one of the cam lobes 2 or 3, as shown in FIGS. 1 and 2, the relatively wide grinding wheels 12 and 13 may first be employed to grind the surfaces of the cam lobes 2 and 3, and then the grinding wheel 12 may be shifted axially to grind the outer surface of the middle cam lobe 4.

Having fully described our invention, it is to be understood that we are not to be limited to the details herein set forth but that our invention is of the full scope of the appended claims.

We claim:

1. For use with an internal combustion piston engine having a main combustion chamber provided with a main intake valve and an exhaust valve, and having an auxiliary combustion chamber provided with an auxiliary intake valve, the improvement comprising: a rotary camshaft having three axially spaced cam lobes integrally formed thereon for actuating said three valves, respectively, one cam lobe being positioned between the other two cam lobes and having greater radial dimensions than one of the other cam lobes at every angular position of the shaft.

2. For use with an internal combustion piston engine having a main combustion chamber provided with a main intake valve and an exhaust valve, and having an auxiliary combustion chamber provided with an auxiliary intake valve, the improvement comprising: a rotary camshaft having three axially spaced cam lobes integrally formed thereon for actuating said three valves, respectively, one cam lobe being positioned between the other two cam lobes and having a silhouette larger than one of the other cam lobes at every angular position of the shaft. 

1. For use with an internal combustion piston engine having a main combustion chamber provided with a main intake valve and an exhaust valve, and having an auxiliary combustion chamber provided with an auxiliary intake valve, the improvement comprising: a rotary camshaft having three axially spaced cam lobes integrally formed thereon for actuating said three valves, respectively, one cam lobe being positioned between the other two cam lobes and having greater radial dimensions than one of the other cam lobes at every angular position of the shaft.
 2. For use with an internal combustion piston engine having a main combustion chamber provided with a main intake valve and an exhaust valve, and having an auxiliary combustion chamber provided with an auxiliary intake valve, the improvement comprising: a rotary camshaft having three axially spaced cam lobes integrally formed thereon for actuating said three valves, respectively, one cam lobe being positioned between the other two cam lobes and having a silhouette larger than one of the other cam lobes at every angular position of the shaft. 